Determining cosmic microwave background structure from its peak distribution

We present a new method for time-efficient and accurate extraction of the power spectrum from future cosmic microwave background (CMB) maps based on properties of peaks and troughs of the Gaussian CMB sky. We construct a statistic describing their angular clustering - analogously to galaxies, the 2-point angular correlation function, $\xi_\nu(\theta)$. We show that for increasing peak threshold, $\nu$, the $\xi_\nu(\theta)$ is strongly amplified and becomes measurable for $\nu\geq$1 on angular scales $\leq 10^\circ$. Its amplitude at every scale depends uniquely on the CMB temperature correlation function, $C(\theta)$, and thus the measured $\xi_\nu$ can be uniquely inverted to obtain $C(\theta)$ and its Legendre transform, the power spectrum of the CMB field. Because in this method the CMB power spectrum is deduced from high peaks/troughs of the CMB field, the procedure takes only $[f(\nu)]^2N^2$ operations where $f(\nu)$ is the fraction of pixels with $|\delta T|\geq\nu$ standard deviations in the map of $N$ pixels and is e.g. 0.045 and 0.01 for $\nu$=2 and 2.5 respectively. We develop theoretical formalism for the method and show with detailed simulations, using MAP mission parameters, that this method allows to determine very accurately the CMB power spectrum from the upcoming CMB maps in only $\sim(10^{-4}-10^{-3})\times N^2$ operations.Comment: To be published in Ap.J. Letters. Minor changes to match the journal versio

On the Presence of Thermal SZ Induced Signal in the First Year WMAP Temperature Maps

Using available optical and X-ray catalogues of clusters and superclusters of galaxies, we build templates of tSZ emission as they should be detected by the WMAP experiment. We compute the cross-correlation of our templates with WMAP temperature maps, and interpret our results separately for clusters and for superclusters of galaxies. For clusters of galaxies, we claim 2-5 $\sigma$ detections in our templates built from BCS Ebeling et al. (1998), NORAS (Boehringer et al. 2000) and de Grandi et al. (1999) catalogues. In these templates, the typical cluster temperature decrements in WMAP maps are around 15-35 $\mu$K in the RJ range (no beam deconvolution applied). Several tests probing the possible influence of foregrounds in our analyses demonstrate that our results are robust against galactic contamination. On supercluster scales, we detect a diffuse component in the V & W WMAP bands which cannot be generated by superclusters in our catalogues (Einasto et al. 1994, 1997), and which is not present in the clean map of Tegmark, de Oliveira-Costa & Hamilton (2003). Using this clean map, our analyses yield, for Einasto's supercluster catalogues, the following upper limit for the comptonization parameter associated to supercluster scales: y_{SC} < 2.18 \time s 10^{-8} at the 95% confidence limit.Comment: MNRAS accepted. New section and minor changes include

Limits on Hot Intracluster Gas Contributions to the Tenerife Temperature Anisotropy Map

We limit the contribution of the hot intracluster gas, by means of the Sunyaev-Zel'dovich effect, to the temperature anisotropies measured by the Tenerife experiment. The data is cross-correlated with maps generated from the ACO cluster catalogue, the ROSAT PSPC catalogue of clusters of galaxies, a catalogue of superclusters and the HEAO 1 A-1 map of X-ray sources. There is no evidence of contamination by such sources at an rms level of $\sim 8\mu$K at 99% confidence level at $5^o$ angular resolution. We place an upper limit on the mean Comptonization parameter of $y \le 1.5\times 10^{-6}$ at the same level of confidence. These limits are slightly more restrictive than those previously found by a similar analysis on the COBE/DMR data and indicate that most of the signal measured by Tenerife is cosmological.Comment: To be published in ApJ (main journal

Large lianas as hyperdynamic elements of the tropical forest canopy

Lianas (woody vines) are an important component of lowland tropical forests. We report large liana and tree inventory and dynamics data from Amazonia over periods of up to 24 years, making this the longest geographically extensive study of liana ecology to date. We use these results to address basic questions about the ecology of large lianas in mature forests and their interactions with trees. In one intensively studied site we find that large lianas (≥10 cm diameter) represent ,5% of liana stems, but 80% of biomass of well-lit upper canopy lianas. Across sites, large lianas and large trees are both most successful in terms of structural importance in richer soil forests, but large liana success may be controlled more by the availability of large tree supports rather than directly by soil conditions. Long-term annual turnover rates of large lianas are 5–8%, three times those of trees. Lianas are implicated in large tree mortality: liana-infested large trees are three times more likely to die than liana-free large trees, and large lianas are involved in the death of at least 30% of tree basal area. Thus large lianas are a much more dynamic component of Amazon forests than are canopy trees, and they play a much more significant functional role than their structural contribution suggests

Missing baryons, bulk flows and the E-mode polarization of the Cosmic Microwave Background

If the peculiar motion of galaxy groups and clusters indeed resembles that of the surrounding baryons, then the kinetic Sunyaev-Zel'dovich (kSZ) pattern of those massive halos should be closely correlated to the kSZ pattern of all surrounding electrons. Likewise, it should also be correlated to the CMB E-mode polarization field generated via Thomson scattering after reionization. We explore the cross-correlation of the kSZ generated in groups and clusters to the all sky E-mode polarization in the context of upcoming CMB experiments like Planck, ACT, SPT or APEX. We find that this cross-correlation is effectively probing redshifts below $z=3-4$ (where most of baryons cannot be seen), and that it arises in the very large scales ($l<10$). The significance with which this cross-correlation can be measured depends on the Poissonian uncertainty associated to the number of halos where the kSZ is measured and on the accuracy of the kSZ estimations themselves. Assuming that Planck can provide a cosmic variance limited E-mode polarization map at $l<20$ and S/N $\sim 1$ kSZ estimates can be gathered for all clusters more massive than $10^{14} M_{\odot}$, then this cross-correlation should be measured at the 2--3 $\sigma$ level. Further, if an all-sky ACT or SPT type CMB experiment provides similar kSZ measurements for all halos above $10^{13} M_{\odot}$, then the cross-correlation total signal to noise (S/N) ratio should be at the level of 4--5. A detection of this cross-correlation would provide direct and definite evidence of bulk flows and missing baryons simultaneously.Comment: 6 pages, 2 figures, submitted to A&

Galaxy Clusters as mirrors of the distant Universe. Implications for the kSZ and ISW effects

It is well known that Thomson scattering of CMB photons in galaxy clusters introduces new anisotropies in the CMB radiation field, but however little attention is payed to the fraction of CMB photons that are scattered off the line of sight, causing a slight blurring of the CMB anisotropies present at the moment of scattering. In this work we study this {\it blurring} effect, and find that it has a non-negligible impact on estimations of the kinetic Sunyaev-Zel'dovich (kSZ) effect: it induces a 10% correction in 20-40% of the clusters/groups, and a 100% correction in $\sim 5$% of the clusters in an ideal (noiseless) experiment. We explore the possibility of using this blurring term to probe the CMB anisotropy field at different epochs in our Universe. In particular, we study the required precision in the removal of the kSZ that enables detecting the blurring term $-\tau_T \delta T / T_0$ in galaxy cluster populations placed at different redshift shells. By mapping this term in those shells, we would provide a tomographic probe for the growth of the Integrated Sachs Wolfe effect (ISW) during the late evolutionary stages of the Universe. We find that the required precision of the cluster peculiar velocity removal is of the order of 100 -- 200 km s$^{-1}$ in the redshift range 0.2 -- 0.8, after assuming that all clusters more massive than 10$^{14}$ h$^{-1}$ M$_{\odot}$ are observable. These errors are comparable to the total expected linear line of sight velocity dispersion for clusters in WMAPV cosmogony, and correspond to a residual level of roughly 900 -- 1800 $\tau_T \mu$K per cluster, including all types of contaminants and systematics. Were this precision requirement achieved, then independent constraints on the intrinsic cosmological dipole would be simultaneously provided.Comment: Notation clarified and typos and errors corrected in eqs.(2-4

Determinación de la estructura genética de las poblaciones silvestres españolas de Castanea sativa mediante isoenzimas

The genetic variability within and among 17 wild Spanish chestnut stands was examined by isozyme analysis, with the goals of describing their geographic structure and designing conservation and management strategies. Measures of genetic diversity such as allelic richness, heterozygosity, polymorphism, F-statistics, D-statistics, gene flow, clustering using Nei’s genetic distances and a method based on an Monte Carlo Markov Chain algorithm and the contributions of each stand to diversity and allelic richness were all used. Wild Spanish chestnut populations displayed heterogeneity of allele frequencies between them, high levels of genetic diversity and high differentiation (Fst = 0.15) compared with populations from other western European countries such as France and Italy. The two clustering methods allowed the identification of three clusters: a Mediterranean cluster, a northern Spanish cluster and the southern Galician cluster. The highest heterozygosity and allelic richness were found in the North, especially in the southern Galician cluster. Several areas can be recommended for inclusion in the network of Conservation Units: Fraga de Catasós, representing the southern Galician cluster; Fragas do Eume, representing the northern Spanish cluster; and Hervás or El Tiemblo, representing the Mediterranean cluster.La variabilidad genética entre y dentro de 17 rodales de castaño silvestre muestreados en poblaciones españolas se examinó mediante el análisis de polimorfismos isoenzimáticos con la finalidad de describir la estructura geográfica y diseñar estrategias de conservación y manejo. Se calcularon la riqueza alélica, heterocigosidad, polimorfismo, la estadística F y D, el flujo genético y se realizaron análisis de agrupación de poblaciones utilizando la distancia genética de Nei y un método basado en el algoritmo Monte Carlo Markov Chain, y finalmente se calcularon las contribuciones de cada rodal a la diversidad y riqueza alélica. Las poblaciones silvestres de castaño españolas presentaron heterogeneidad de frecuencias alélicas entre ellas, elevados niveles de diversidad genética y de diferenciación (Fst = 0.15) comparadas con otras poblaciones del Oeste de Europa. Se identificaron tres grupos de poblaciones: el grupo Mediterráneo, el grupo del Norte y del Sur de Galicia. La mayor heterocigosidad y riqueza alélica está en el Norte, principalmente en el grupo del Sur de Galicia. Se recomiendan varias áreas para incluir en la red de Unidades de Conservación: Fraga de Catasós, en representación del grupo Sur de Galicia; las Fragas do Eume, representando el grupo del Norte; y Hervás o el Tiemblo en representación del grupo Mediterráneo